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Transcript of Optical telecommunication networks. Introduction Multiplexing Optical Multiplexing Components of...
OPTICAL MULTIPLEXING
optical telecommunication networks
OUTLINE Introduction Multiplexing Optical Multiplexing Components of Optical Mux Application Advantages Shortcomings/Future Work Conclusion References
INTRODUCTION Optical transmission uses pulses of light to transmit
information from one place to another through an optical fiber.
The light is converted to electromagnetic carrier wave, which is modulated to carry information as the light propagates from one end to another.
The development of optical fiber has revolutionized the telecommunications industry.
Optical fiber was first developed in the 1970s as a transmission medium.
It has replaced other transmission media such as copper wire since inception, and it’s mainly used to wire core networks.
Today, optical fiber has been used to develop new high speed communication systems that transmit information as light pulses, examples are multiplexers.
MULTIPLEXING Multiplexing
What are Multiplexers? Multiplexers are hardware components that combine
multiple analog or digital input signals into a single line of transmission.
And at the receiver’s end, the multiplexers are known as de-multiplexers – performing reverse function of multiplexers.
Multiplexing is therefore the process of combining two or more input signals into a single transmission.
At receiver’s end, the combined signals are separated into distinct separate signal.
Multiplexing enhances efficiency use of bandwidth.
MULTIPLEXER
MULTIPLEXING EXAMPLE MATLAB simulation example:
Sampled in time: Quantization Digitization
0 10 20 30-10
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10Sinusoidal Signal
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->
Time--->0 10 20 30
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Time--->
0 10 20 30-10
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Time--->0 10 20 30
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Am
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->Time--->
MULTIPLEXING EXAMPLE Multiplexed Signals
Separation of signalsUsing time slots.
0 10 20 30 40 50 60-8
-6
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Time--->
0 5 10 15 20 25 30-10
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Time--->
0 5 10 15 20 25 300
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Time--->
RECOVERED SIGNAL
0 5 10 15 20 25 30-10
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Am
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de--
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Time--->
0 5 10 15 20 25 300
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8Recovered Triangular Signal
Am
plitu
de--
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Time--->
OPTICAL MULTIPLEXING Optical multiplexer and de-multiplexer
are required to multiplex and de-multiplex various wavelengths onto a single fiber link.
Each specific I/O will be used for a single wavelength.
One optical filter system can act as both multiplexer and de-multiplexerLaser 1
Laser 2
Laser 3
Laser 4
Multiplexer Optical Fiber De-multiplexer
Regenerator + Receiver
OPTICAL MULTIPLEXING Optical multiplexer and de-multiplexer are
basically passive optical filter systems, which are arranged to process specific wavelengths in and out of the transport system (usually optical fiber).
Process of filtering the wavelengths can be performed using: Prisms Thin film filter Dichroic filters or interference filters
The filtering materials are used to selectively reflect a single wavelength of light but pass all others transparently.
Each filter is tuned for a specific wavelength
OPTICAL MULTIPLEXING AND FILTERING
COMPONENTS OF OPTICAL MULTIPLEXER Combiner Tap Coupler
ADD/DROP Filters
PrismsThin filmDichroic
Splitter Optical fiber
OPTICAL MULTIPLEXING TECHNIQUES There are different techniques in multiplexing light
signals onto a single optical fiber link. Optical Multiplexing Techniques
Optical Time Division Multiplexing (OTDM) Separating wavelengths in time
Wavelength division multiplexing (WDM) Each channel is assigned a unique carrier frequency Channel spacing of about 50GHz
Coarse Wavelength Division Multiplexing (CWDM) Dense Wavelength Division Multiplexing
Uses a much narrower channel spacing, therefore, many more wavelengths are supported.
Code Division Multiplexing Also used in microwave transmission. Spectrum of each wavelength is assigned a unique spreading
code. Channels overlap both in time and frequency domains but the
code guide each wavelength.
APPLICATIONS The major scarce resource in telecommunication
is bandwidth – users want transmit at more high rate and service providers want to offer more services, hence, the need for a faster and more reliable high speed system.
Reducing cost of hardware, one multiplexing system can be used to combine and transmit multiple signals from Location A to Location B.
Each wavelength, λ, can carry multiple signals. Mux/De-Mux serve optical switching of signals in
telecommunication and other field of signal processing and transmission.
Future next generation internet.
ADVANTAGES High data rate and throughput
Data rates possible in optical transmission are usually in Gbps on each wavelength.
Combination of different wavelengths means more throughput in one single communication systems.
Low attenuation Optical communication has low attenuation
compare to other transport system. Less propagation delay More services offered Increase return on investment (ROI) Low Bit Error Rate (BER)
SHORTCOMINGS Fiber output loss + dispersion
Signal is attenuated by fiber loss and distorted by fiber dispersion
Then regenerator are needed to recover the clean purposes
Inability of current Customer Premises Equipment (CPEs) to receive at the same transmission rate of optical transmitting systems. Achieving all-optical networks
Optical-to-Electrical conversion overhead Optical signals are converted into electrical signal using
photo-detectors, switched and converted back to optical. Optical/electrical/optical conversions introduce unnecessary
time delays and power loss. End-to-end optical transmission will be better.
FUTURE WORK Research in optical end user equipment
Mobile phones, PC, and other handheld devices receiving and transmitting at optical rate.
Fast regeneration of attenuated signal Less distortion resulting from fiber
dispersion. End-to-end optical components
Eliminating the need for Optical-to-Electrical converter and vise versa.
CONCLUSION Optical multiplexing is useful in signal
processing and transmission.Transporting multiple signals using one single
fiber linkThe growth of the internet requires fiber optic
transmission to achieve greater throughput.Optical multiplexing is also useful in image
processing and scanning application. Optical transmission is better compare to
other transmission media because of its low attenuation and long distance transmission profile.
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